An installation featuring thousands of moving images of clocks edited together to show real time will open in London this week. United States artist Christian Marclay's piece, entitled The Clock 2010, is a montage of scenes from the world of film and television. "It is a thrilling journey through cinematic history as well as a functioning timepiece," the Tate Modern said of the piece on its site. It took the artist several years to trawl through footage in order to collect enough material, according to the museum. Visitors will be able to see the installation for free during the day while once a month the Tate Modern will remain open to allow the full 24-hour installation to be shown. The show opens to the public from September 14 to January 20. Australian Associated Press